Neuro Exam 3 Lecture 2

Front 1

Descending pathways are related to somatic motor, which are the:

Back 1

voluntary control systems by which we perform movements

Front 2

The somatic motor pathways are _____ neuron pathways (for the most part)

Back 2

2

- 2 neurons from the CNS to muscle contraction

Front 3

What are the two neurons in a somatic neuron pathway?

Which is the first neuron in the pathway?

Back 3

-Upper motor neurons (UMNs)- first neuron in the pathway

-Lower motor neurons (LMNs)- the final neuron in the pathway

Front 4

What is the somatotopic (body wall) organization within the motor cortex? (what is it arranged by)

Back 4

Arranged by myotomes, not dermatomes

Front 5

What are the two somatic motor pathways from the motor cortex?

Back 5

-corticospinal tract

-corticonuclear tract

Front 6

The corticospinal tract originates in the ____1______ and projects to the ______2_______

Back 6

1. cortex

2. spinal cord

Front 7

the corticonuclear tract goes from the ______1___ to specific _____2_______

Back 7

1. cortex

2. nuclei

Front 8

There are some additional brainstem-spinal systems that originate in various gray matter regions within the brainstem and project to the spinal cord. What are they?

Back 8

-Vestibulospinal tract

-reticulospinal tract

-rubrospinal tract

Front 9

What do upper motor neurons do?

Back 9

Influence the activity of lower motor neurons (LMNs)

Front 10

Are upper motor neurons named for their location?

Back 10

No, upper motor neuron has nothing to do with location- they can be found in the primary motor cortex, but also in certain brainstem nuclei

Front 11

Cell bodies of UMNs are located in the __________ and ___________

Back 11

-primary motor cortex

-brainstem

Front 12

Axons of UMNs synapse on LMNs located in the ___________________ or the ______________

- where specifically?

Back 12

-brainstem (cranial nerve nuclei)

-spinal cord (anterior horn)

Front 13

LMNs directly innervate:

Back 13

skeletal muscles

Front 14

Neurons in the premotor cortex or the supplementary motor cortex project to do what to cells in the primary motor cortex?

Back 14

Neurons from these cortexes can activate or inhibit cells in the primary motor cortex

Front 15

How do we define a neuron to be an upper motor neuron?

Back 15

if it influences the activity of lower motor neurons -- neurons that control the activation of other neurons

Front 16

What is the final common pathway?

Back 16

where the axon of a lower motor neuron forms a neuromuscular junction synapse with a skeletal muscle and directly produces muscle contraction

Front 17

Lower motor neurons can be found in _____1_____ and _____2_____, and from both, the LMNs can project out to _________3_________ for motor output

Back 17

1. brainstem nuclei
2. the spinal cord

3. skeletal muscle

Front 18

The primary motor cortex can also be called: (three things)

Back 18

-M1

-Precentral gyrus

-Brodmann's area 4

Front 19

What are M1 cells?

Back 19

Motor neurons with cell bodies in the primary motor cortex

Front 20

Together, the premotor cortex and the supplementary motor cortex make up:

Back 20

Brodmann's area 6

Front 21

With the whole process of movements, we can use a ready, set, go process from the motor cortices in the cerebral cortex. What would the 'ready' portion be?

Back 21

The supplementary cortex- gets the body READY to produce a particular movement

Front 22

What does the supplementary cortex do?

Back 22

Plans the sequence of muscle activation required to perform the movement (for example, planning to stand up, planning to reach and grasp something)

Front 23

In the ready, set, go analogy for the motor cortices, what portion of the cerebral cortex is "set"?

Back 23

premotor cortex

Front 24

In the ready, set, go analogy for the motor cortices, what portion of the cerebral cortex is "GO"?

Back 24

primary motor cortex

Front 25

If you are doing random finger movements, which area of the cortex is activated? (no actual planning and no real sequence)

Back 25

Only the hand area of M1 (primary motor cortex)

Front 26

If you are told to move your fingers in a planned sequence, and then they are moved in the sequence, what is activated? (ex- first move your ring finger, then your index finger, and then your pinky)

Back 26

The supplementary motor cortex and the hand area of M1 (premotor cortex)

Front 27

If you are told to move your fingers in a planned sequence, and the finger movements are mentally planned and rehearsed in your mind but not actually executed, what is activated?

Back 27

The supplementary motor cortex

Front 28

In the planning of movements, what does the premotor cortex do?

Back 28

cells in premotor cortex set the limb for a particular movement-- it sets the proper posture for the limb in which the movement is initiated. For example, they position the upper limb for effective use of the hand

Front 29

neurons in the premotor cortex are active immediately prior to the:

Back 29

M1 cells

Front 30

Where does the premotor cortex receive input from?

Back 30

The parietal lobe

(the somatosensory system like your proprioceptors)

Front 31

the _______________ sets the posturing to allow the movement to occur

Back 31

premotor cortex

Front 32

How do your motor cells know : here's where I am now?

Back 32

The proprioceptors from your somatosensory cortex send information to your motor cells in the premotor cortex

Front 33

The neurons from the premotor cortex project to __________ that innervate proximal limb muscles to set the proper posture required for initiation of the intended movement (i.e., position the upper limb for effective use of hand)

Back 33

M1 cells, or primary motor cortex

Front 34

Are the neurons in the premotor cortex involved in the actual execution of the movement?

Back 34

no, that role is primarily M1 cells in the primary motor cortex

Front 35

_________ is the primary player in the descending pathways from the cortex that provides the actual movement

Back 35

M1 (the "go" signal)

Front 36

Do M1 cells directly synapse on skeletal muscles to produce the movement?

Back 36

No, These are the UMNs, and they influence the activity of the lower motor neurons that innervate the skeletal muscles

Front 37

__________ in the primary motor cortex are necessary for fine motor control and fractionation

Back 37

M1 cells

Front 38

What is fractionation?

Back 38

The ability to individually activate specific muscles independent of other muscles to produce specific movements.

(selective activation and inhibition of muscles in the distal extremities)

Front 39

The ability to independently move your thumb from your first digit or second digit and so on is and example of:

Back 39

fractionation

Front 40

Which pathway allows for fractionation to occur (fractionation is very important in most of the fine motor control that we have)?

Back 40

The corticospinal tract

Front 41

What is the Acronym for remembering somatotopic organization in the motor cortex?

Back 41

FUL

F-Face (most inferior on lateral cortex-)
U-Upper limb (superior on lateral cortex)
L-Lower limb (superior on medial cortex)

Front 42

Somatotopic organization is in the:

Back 42

precentral gyrus (M1, primary motor cortex, Brodmann's area 4)

Front 43

The Face portion of the somatosensory organization in the motor cortex is located superior to ___1_______ and anterior to ______2_____

Back 43

1. lateral fissure

2. central sulcus

Front 44

The UMNs in the motor cortex project to the _________ and ________

Back 44

spinal cord and brainstem

Front 45

What are the descending pathways that begin in the primary motor cortex?

Back 45

-corticospinal tract

-croticonuclear tract

Front 46

The UMNs in the brainstem project to the:

Back 46

spinal cord

Front 47

What are the descending pathway that begin with upper motor neurons in the brainstem?

Back 47

-rubrospinal tract

-vestibulospinal tract

-reticulospinal tract

Front 48

What is a more archaic term used to describe the corticonuclear tract? why?

Back 48

The corticobulbar tract. Bulb is an archaic term used to describe the medulla oblongata

Front 49

In humans, what is the most important pathway for movements of the limbs?

Back 49

the corticospinal tract

Front 50

Tell me generally about the corticospinal tract?

Back 50

The corticospinal tract ortiginates in the primary motor cortex and it is a contralateral system. This pathway is primarily important in the execution of fractionated movements in the distal extremities

Front 51

Which pathway is primarily important in the execution of fractionated movements in distal extremities?

Back 51

the corticospinal tract

Front 52

Is the corticospinal tract a contralateral or an ipsilateral system? What does this mean?

Back 52

Contralateral. So upper motor neurons from the right primary motor cortex will synapse on lower motor neurons that control muscles on the left side of the body

Front 53

The ______________ pathway is an analogous pathway to the corticospinal tract, except it is used in movements of the head and neck

Back 53

corticonuclear tract

Front 54

Is the corticonuclear tract a contralateral or ipsilateral pathway?

Back 54

It can't be considered just one or the other; each brainstem nucleus has to be considered individually because sometimes it receives bilateral connections, sometimes only ipsilateral, and sometimes predominantly contralateral connections, so this pathway isn't crossed or uncrossed, but rather depends on each distinct cranial nerve nuclei

Front 55

the corticonuclear tract does not synapse on lower motor neurons associated with cranial nerves ______, _______, or _______.

Back 55

CN III
CN IV
CN VI

Front 56

What is an overview of the vestibulospinal tract?

Back 56

It is a predominantly ipsilateral pathway, and travels from vestibular nuclei to ipsilateral spinal LMNs (all levels of spinal cord), specifically to more paravertebral and proximal limb extensor muscles- so muscles relating to the trunk and the proximal limbs- e.g. the shoulder girdle

Front 57

______________ is an important pathway for balance and equilibrium (and posture)

Back 57

vestibulospinal tract

Front 58

the vestibular apparatus projects to cells of the vestibular nuclei to provide:

Back 58

postural adjustments- predominantly related to extensor muscles that help us balance

Front 59

The vestibulospinal tract is a "feedback" pathway... what does this mean?

Back 59

it does not get cortical input, it is a reflexive sort of pathway, its not a voluntary pathway per say, the inputs are predominantly from vestibular nuclei

Front 60

The reticulospinal tract is predominantly what type of pathway?

Back 60

ipsilateral

Front 61

in the reticulospinal tract, the primary influence is on:

Back 61

trunk and limb extensor muscles related to postural support

Front 62

The reticulospinal tract travels from the ____________ to ___________

Back 62

reticular formation to ipsilateral spinal LMNs (all levels)

Front 63

Why is the reticulospinal tract considered a "feed forward" pathway?

Back 63

because it does receive cortical input, meaning the reticulospinal tract goes from the reticular formation to the spinal cord, but there are cortical neurons that influence the activity of those upper motor neurons, so there is the possibility for cortical input

Front 64

The cells of origin for the Rubrospinal tract are in the __________

Back 64

red nucleus

Front 65

What type of pathway is the rubrospinal tract?

Back 65

contralateral (projects to control muscles on the opposite side of the body)

Front 66

Which pathway is very important in animals but is only rudimentary in humans?

Back 66

The rubrospinal tract

Front 67

What is the origin of the corticospinal tract?

Back 67

The predominant source of upper motor neurons in this pathway arise from the
primary motor cortex

Front 68

What is the course of the corticospinal tract?

Back 68

From the primary motor cortex, it descends down through the posterior limb of the internal capsule, then to the crus cerebri (cerebral peduncle- in midbrain), then continue to descend through the basilar pons, down to the medullary pyramid, then pyramidal decussation (at the spinomedullary junction), to the lateral corticospinal tract in the spinal cord, where it then synapses on LMNs in the contralateral anterior horn of the spinal cord

Front 69

Where does the corticospinal tract terminate? (synapse)

Back 69

On LMNs in the contralateral anterior horn of the spinal cord

Front 70

Go back through slide 13-21 to look at pathway

Back 70

of corticospinal tract

Front 71

In the corticospinal tract, everything above the level of the spinal cord is called the corticospinal tract, but once it is in the spinal cord, it is called the:

Back 71

Lateral corticospinal tract

Front 72

Go review structures

Back 72

:)